Two-cycle internal-combustion engine employing liquid fuel.



H. JUNKERS. Two CYCLE INTERNAL GOMBUSTION ENGINE BMPLQYING LIQUID FUEL.

APPLI'ATION FILED AUG. 28, 1908.

Patented Nov. 17, v1914.

ff Wiley HUGO JUNKERS, OF AIX-LA-GHAPELLE, GERMANY.

TWO-CYCLE INTERNAL-COMBUSTION ENGINE EMPLOYING LIQUID FUEL.

Specification of Letters Patent.

Patented Nov. 17, 1914.

Application led August 28, 1908. Serial No. 450,775.`

To all whom it may concern:

Be it know-n that I, HUGO .IUNKERa a Y subject of the King of Prussia, residing at others skilled in the art to which it appertains to make and use the same.

The present invention has for its object to provide an engine for the development of power from liquid fuel such as hydro-earbon oils, and particularly from crude or so-called heavy oils, in such manner as to attain good thermic efficiency combined with the assurance of uninterrupted opera-` tion, good starting qualities and the possibilit of 'controlling the speed and output of t e engine over rather Wide limits. To this end, a type of engine is employed in which the gas used for supporting combustion, and which I will hereinafter refer to as the air, is, without ythe adrnixture of any combustible material, compressed in the engine cylinder to; a temperature well above the ignition point of the fuel employed, and the liquid fuel is then introduced in a finely divided form beginning at or near the end of the compression stroke, and continuing through the dead point and a portion of the working stroke, the duration of the admission of fuel in the working Vstroke determining the output of the engine. That is to say, the engine is of the slow combustion,

or so-called equal pressure type, of .which the well-known Diesel engine is the most prominent example. In the following portions of this specification I will use the term slow combustion engine in this sense, and

in contradistinction to engines of the explosion type, that is, engines in which a combustible `mixture is compressed and ignited either by the heat due to compression or by a suitable ignitin'g device. I have found that the successful development of an engine of this slow combustion 'type and having capacities above indicated is dependent primarily upon efficient compression approaching as nearly as possible ideal adiabatic conditions, which involves a rapid compression into a combustion space or chamber in which heat losses by conduction through the walls of the chamber are reduced to a minimum; and secondarily, upon efficient scavenging whereby the products of combustion are completly removed at each scavenging operation and soot-free combustion is attained, while at the Same time the air is introduced in a cool and heavy state so that a maximum uantity of air is inclosed in the cylinder at t e time compression begins. I have therefore employed, in the embodiment of my invention, a type of engine which isv an adaptation of an already known type in such manner that it is enabled to fulfil the conditions just indicated. This engine is characterized by the em loyment of a cylinder of smooth bore wit out projections or recesses and in which the ratio of length to the volume is relatively' great, and in which operate two opposedly working pistons, the pistons and cylinder being so proportioned to the intended speed of the stroke as to compress the air to a temperature well above the ignition point of the fuel employed before the fuel is introduced. The cylinder is provided with exhaust passages at one end and inlet passages `at the other end, the paages being preferably controlled by the pistons and so shaped and arranged that the exhaust passages will open before the air passages are opened and will close after the air passages are closed. With this construction there is provided an effective cylinder space from which the products of combustion are driven out by a straight continuous air stream entering the working cylinder at one 'end and leaving it at the opposite end; and combustion takes place in a combustion chamber where the heat losses are reduced to a minimum since it has not only a relatively small wall area, but the hot piston faces constitute the greater part ofl that area,which is free from inlet and exhaust valves which would necessarily be cooled by the scavenging air. Furthermore the heating of the air charge is reduced to a minimum since the air does not-pass 'over hot valve surfaces and at the beginning of the compression the effective cylinder chamber has-a maximum cooled sul face, z'. e., the walls of.

the cylinder which are. cooled by the water jacket, se that the charge of air` is cool and. heavy and consequently of large amount.

In the accompanying drawings, which illustrate the preferred embodiment of my invention-Figure '1 is a longitudinal sectional view of the engine; Fig. 2 is a plan View; Fig. 3 is a sectional viewon lines 3, 3 of Fig. 1; Fig. 4 is a sectional View on line 4, 4 of Fig. 1; and Fig. 5 is a typical working diagram of my improved engine in com? parison with a diagram of a slow combustion engine in which but a single piston is employed.

To the frame 1 the working cylinder 2, the

i reach 3, the cylinder ofthe scavenging and joined by the cross-head 13 which slides in the cross-head guides 14. The other working piston 15 is connected by the piston rod 16 to the reciprocating yoke 17I mounted in guides in the reach 3 and connected by the rods 18 tothe cross-heads 19 which slide upon the slides 20 and are connected through the connecting "rods 21 to the. two outer cranks displaced about 180o from the middle -crank of the crank shaft 9., The connecting rod 11 and the piston rod 12 on the one hand and the 4connecting rods 22, side rods,

18 and piston rods 16 on the other hand are so dimensioned with respect to the dimensions of the cylinder and pistons that when the pistons 10 and l5 have reached their position of closest approach the air will have been compressed to a temperature aufficiently high to insure ignition of the lifiguid fuel employed at all speeds at which the Y engine is intended to operate. rThe opposing end walls of the two pistons and the cylinder walls forming the combustion chamber are without any essential projections or recesses, which would tend to increase the surface of the combustion chamber and'thereby increase the heat losses at the periods of high temperature, that is during the last part of the compression stroke and the rst part of the working stroke. The piston rod 22 of the piston 23 of the scavenging and air supply pump 4 is secured to the end of the piston rod 16, and the plunger 24 of the atomizer or vaporizing pump is carried by the piston 23 (see Fig. l). 'llhe end of the working cylinder 2 adjacent t0 the frame 1 is provided with an annular set of exhaust openings 25 which communicate with the eX- haust port 26 by means of the annular space 27 and the elbow 28. The opposite endof the working cylinder-2 is provided with a set of air inlet openings 29, which communicate by means of the annular space 30 with the pump 31 whose rear end communicates with 'the slide valve box of the air pump 4. rlhis pump 3l is made large enough to serve as a reservoir.

On top of the working cylinder 2 and at the central portion thereof, the fuel valve 32 is arranged and connected by the pipe 33 to the rear of the air pump 5. Between said pipe 33 and the cylinder of said air pump 5 the pressure valve 34 operates, while the suction valve 35 of the pump is arranged opposite to and below the pressure valve.

To operate the fuel valve 32 the fuel pump 36 and the slide valve 37 of the air pump 5, aworm 38 is mounted upon the crank shaft 9 which by means of the worm wheel 39 imparts rotation to theV shaft 40, the motion of which .is in turn transmitted to the shaft 41 by-means of the pinions 42 and 43. The motion of shaft 41 is transmitted to shaft 44 by means of the worm 45 and the worm wheel 46. To one end of the shaft 44 an adjustable clamp pin 47 is secured and connected by means of thel connecting rod f 48 to the plunger of the fuel pump 36 (see Figs. 1 and 3). Upon the shaft 41 is mounted a cam 49 which periodically imparts motion to the lever 50 whose shorter end is connected by means of the rod 51 to the lever 52, the inner end of which operates the fuel valvel 32. The fuel valve closes and opens a communication between the working cylinder and the high pressure air pipe 33 and the fuel pipe 53 leading from the fuel pump 36.

The engine operates as follows: Shortly before-the working pistons 10 and 15 have reached their outer dead points the working piston 10 uncovers the exhaust openings 25 through which the products of combustion of the previous working stroke escape. Immediately after this the working piston 15 uncovers the inlet openings 29 through which the scavenging and charging air rushes -in from the pipe or receiver 31 to drive out the remainder of the products of combustion from the cylinder 2 and also to refill the latter with fresh air. During the following compression stroke of -the two working pistons the charging air is so highly compressed that it reaches a temperaturc sufficiently high to ignite the fuel employed, which enters the working cylinder 2 tons 10 and 15 when they have almost reached their inner dead points. The fuel valve 32 is operated when the projection of cam 49 comes into contact with the lever 50, at which instant the atomizing air, which during ythe previous working stroke was highly compressed, blows the fuel, which has been delivered by the fuel pump 36, in a finely atomized or. vaporized condition into the working cylinder 2 wherein it is ignited by the highly compressed charging air. The admission of fuel into the working cylinder 2 is continued during a part of the working stroke, which can be done in such manner that the resulting rise of temperature is, because of the increase of volume, unaccompanied by a substantial change of pressure, at any rate, not in such a de ree as in the explosion engine. After the uel valve 32 has been closed, the expansion of the hot gases takes place and continues until near the close of the working stroke, when the working piston 10 uncovers the outlet openings 25 again, whereupon the scavenging of the working cylinder 2 begins anew.

Fig. 5 represents a working diagram of my improved engine in comparison with a diagram of a single-piston slow combustion engine, such as is now in common use, in which diagram a represents the expansion curve of my improved engine and b the eX- pansi'on curve of the single-piston engine. The difference between the hatched areas c and d shows the useful work gained per stroke by the new engine as compared with the old engine under otherwise the same conditions. This difference in thermal efficiency is based upon the proportions of the different cylinder surfaces of these two engines and is most favorably influenced by the fact that the fuel is injected midway between the two working pistons when in or near their innermost positions, and by the fact that the opposing faces of the two pistons and the cylinder walls are without any essential projections or recesses whatever. For the compression curve the double-piston engine is -lkewise advantageous, since with the same compression a higher temperature is attained, which in turn assures a better ignition and a more complete combustion of the fuel' employed. ABesides this a higher temperature facilitates the starting of the engine and the combustion of diflicultly ignitible fuel is made possible. As a result of these conditions, it becomes possible not only to develop the power with greater thermic efficiency, but also to produce an engine which, burning the heavy oils, will bev capable of a regulation of speed and output within wide limits, so much so that it as in practice been found possible to vary fthe speed of an engine of this type from 250 revolutions per minute to 30 revolutions culty with the ignition; a result which so far as I am aware, has not been hereto ore attained.

Vhat I claim is: j

1. Ina slow combustion two-cycle engine, a cylinder having air inlet passages at one end and exhaust passages for the products of co-mbustion at the other end, and two opposedly working pistons in the cylinder which at their point of nearest approach deline with the central portion of the cylinder a combustion chamber of small wall area, said parts being so proportioned as to compress the air well above the ignition temperature of the fuel employed, whereby there is attained good scavenging with low temperature ol the air charge before compression, rapid compression at relatively low piston speeds and minimum heat losses du'ring the periods of high temperature, in combination with means for injecting fuel into the combustion chamber .after the temperature of the air has been brought by compression well above the ignition temperature of the fuel; substantially as described.

2. In a slowr combustion two-cycle engine, a cylinder of small diameter relative to its effective volume and of smooth bore substantially. without recesses or projections having air inlet passages at one end and exhaust passages for the products of combustion at the other end, and two opposedly working pistons in the cylinder which at their point of nearest approach define with the central portion of the cylinder a combus-lOO 4tion chamber of small wall area, said parts being so proportioned as to compress the air -well above the ignition ,temperature of the vand minimum heat losses during the periods of high temperature, in comblnation with means for injecting fuel into the combustion chamber after the temperature of the' air has been brought by compression Well above the ignition temperature of the fuel; substantially as described. i

3. In a slow combustion two-cycle engine, a cylinder of small diameter relative to its effective volume and with a smooth bore substantially without projections or recesses having air inlet passages at one end and eX- haust passages for the products of combustion at the other end, and two opposedly working pistons in the cylinder which at their point of nearest approach define with the central portion of the cylinder a' combustion chamber of small wall area, said parts being so proportioned as to compress the air well above the ignition temperature of the fuel employed, and the exhaust passages being opened before the inlet passages are opened, whereby there is attained good scavenging with low temperature of the Yaill charge before colnpession, rapid compression at relatively 10W piston speeds and minimum heat losses during the periods of high temperature, in combination With means lfor injecting fuel into the combustion ohambei" after 'the temperature of the air l0 has been brought by Compression Well above 1,1 iene? the ignition temperature of the fuel; slb stantially as described.

ln testimony whereof Lhave signed my name to this specicationvn the presence of two subscribing Witnesses.

HUGO JUNKERS.

Witnesses: f HENRY QUADFLIEG, RLISE KALBURSH. 

